District cooling system has gain more and more attention in the past decade since its high efficiency of energy generation. This paper proposes a district cooling system with a large ice tank as low-cost energy storage, which can significantly save operating cost of the whole system. With the ice tank, cooling load at the peak time can be transferred to the trough periods, which helps reduce power supply pressure of power grid in summer, so as to enhance the stability of the power system. Furthermore, multi-objective optimization method is used to deal with the high-loss problem of this cooling system. A new operation scheme is designed considering both energy efficiency and operation cost. The scheme provides adjustable running points for system operator to choose according to management requirements. Compared with single object optimization, the new operation modes can reduce system loss in different degree while keeping a relatively low operation cost.